Mild thyroid failure is a common condition among older adults and has been associated with numerous adverse effects on health, such as cardiovascular disease, cognition disturbances and muscular problems. Mild thyroid failure has also been associated with an increased risk of developing depression. To date, only few studies have investigated the effect of thyroid hormone replacement on depression in patients with mild thyroid failure. This study therefore aims to assess whether thyroid hormone replacement in older adults with mild thyroid failure is associated with a decrease in the presence of depressive symptoms. This study forms a substudy of a large international study on thyroid hormone replacement in older adults with mild thyroid failure (the TRUST study).

The intervention will start with Levothyroxine 50 µg daily (reduced to 25 µg in subjects <50Kg body weight or if known coronary heart disease - previous myocardial infarction or symptoms of angina pectoris) versus matching placebo; at 3 months if the serum TSH level is <0.4 mU/L dose will be reduced by 25 µg; TSH >=0.4 and <4.6 mU/L, no change to dose; TSH >=4.6mUL, additional 25 µg. The process will be repeated at 12 months then annually. Mock titration will be performed in the placebo group. The maximum possible dose of Levothyroxine that will be prescribed is 150μg (after 4 increments of 25μg at 3 months, 1, 2 and 3 years; from the starting dose of 50μg).

Placebo Comparator: 2

Placebo Control Group

Drug: Placebo

Placebo

Detailed Description:

Background

Subclinical hypothyroidism is a common condition among older adults, particularly above the age of 65 years, with a prevalence reaching 10 to 15% of the population. This condition has been associated with numerous adverse outcomes, such as cardiovascular disease, cognition disturbances and muscular problems. All of these potential outcomes will be assessed in the TRUST study. Subclinical hypothyroidism has also been associated with an increased risk of developing depression. It has been suggested that subclinical hypothyroidism may lower the threshold for the development of depression. The prevalence of depression among community-dwelling elderly ranges from 2 to 10%. Patients with depression have been shown to have a lower response to anti-depressive drugs when they have subclinical hypothyroidism. Only a few randomized studies in patients with subclinical hypothyroidism have studied the effect of thyroid hormone replacement on depression, with conflicting results: the studied populations were often small (maximal number of participants: 143), using different scales to measure the presence of depressive symptoms.

Objective

To investigate whether thyroid hormone replacement in older adults with subclinical hypothyroidism is associated with a decrease in the presence of depressive symptoms in a sub-study of the TRUST study.

Methods

Use of the 15-item Geriatric Depression Scale (GDS-15) to measure depressive symptoms in all 1500 patients included in the TRUST study in Switzerland and the Netherlands, the most validated test for depression screening, with validity to measure longitudinal changes. GDS-15 will be applied at baseline and after 1 year to compare changes in depression scores between placebo and thyroxin arms. Power calculation (ANCOVA method) with 750 participants per treatment group, assuming a standard deviation of 3 and a baseline to follow up correlation of 0.7, results in 100% power for detecting a mean difference of 0.5 points at a two-sided alpha-level of 0.05. Depending on recruitment for the main trial (clinicaltrials.gov ID: NCT01660126) in respective countries, a lower number of participants may be included, retaining a very large power for this continuous outcome.

Subjects who are participating in ongoing RCTs of therapeutic interventions (including CTIMPs)

Plan to move out of the region in which the trial is being conducted within the next 2 years (proposed minimum follow-up period)

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Please refer to this study by its ClinicalTrials.gov identifier: NCT01853579